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The minute hand of a clock is 15 cm long. Calculate the area swept by it in 20 minutes.
Length of minute hand = 15 cm
Here, the length of the minute hand is equal to the radius of the sector formed by the minute hand.
Angle made by the minute hand in 1 minute = = 6°
Angle made by the minute hand in 20 minutes = 20 × 6 = 120°
Here, the area swept by the minute hand is equal to the area of the corresponding sector made.
∵ Area of sector = × πr2
= × 3.14 × 15 × 15 = 235.5 cm2
Hence, the area swept by it in 20 minutes is 235.5 cm2.